I thought it was flipped at first too...but when zoomed in, what looks like a door with the white frame windows - doesn't look like a door any more. It's just "drippage" from the rain gutter/eyebrow over the window.
I agree, it could also be a
1936/37 Pierce Arrow Travelodge they have the really curvy/round high wheel wells too. But I don't see the prominent horizontal stripes or panel segments on the photo as in the Pierce Arrow ad.
Regardless, looks like it could be a very cool trailer...would love to know more about it.
Shari